How does everyone feel about the answer from <@U092N7GGG> here? I personally really like using !! wh...

# announcements

[Colton Idle]

How does everyone feel about the answer from @yole here? I personally really like using !! when I want to assert that something is not null at that point.
https://discuss.kotlinlang.org/t/requirenotnull-or/1562/2

[spand]

It provides a shitty debugging experience without any reason for the error

[spand]

I try to never use !! in my code

[marstran]

Using requireNotNull expresses intent more clearly.

[sindrenm]

Agree in avoiding bang-bang (unless it's a reference to Jessie J, Ariana Grandle and Nicki Minaj). requireNotNull and checkNotNull express intent more clearly, or when it makes sense just using `if`s with smart-casting. 😎

[Burkhard]

The one place i use !! is to tell kotlin that a platform type is not null, e.g. someJavaCall()!!

[elizarov]

I read !! as “require not null”

[Colton Idle]

@elizarov thoughts on this post? https://fragmentedpodcast.com/episodes/176/

Donn walks through why Kotlin’s Not Null Assertion Operator (!!) is a code smell and what you can do to alleviate it.

[elizarov]

Have not listened to it. Is there a transcription available?

[Colton Idle]

Unfortunately not. 😭

[cedric]

The podcast basically says never to use !!, except maybe in tests.

[cedric]

I think it’s a bit too strong, there are cases even in production code where things should absolutely never be null (e.g. a configuration file should be part of the distribution). Your app is going to crash if that thing is null, so it’s all a matter of how you want to crash.

[Colton Idle]

Yeah. @cedric personally I prefer to crash if I know it should never be null, but it sounds like the podcast author uses some other techniques, but I haven't found anything as easy to use as !!.

[elizarov]

You can use ?: error("This should not happen"). I guess a project might have a policy to provide a better message that includes a context in this case. That would be a material improvement over !!. Without additional context in a message I see no benefit in writing longer code, though.

[sindrenm]

The “better error” part here is also a reason why I prefer `requireNotNull`/`checkNotNull` over !!. 👍

[spand]

How do you remember which is which ?

[sindrenm]

require vs check? I … don't know, I guess I just remember that require is in the context of arguments, where check is in the context of state, but I'm not sure why. 😛

[Colton Idle]

@sindrenm I tried to just do a requireNotNull check, but it didn't do anything because my value was mutable, so I still had to use !! or ? in line when accessing the variable.

[sindrenm]

requireNotNull<T?> returns the T (non-nullable, so you could potentially do this:

val value = requireNotNull(nullableValue)

// use value henceforth

[sindrenm]

Or, you could also inline the requireNotNull(value) calls to wherever you're accessing value, but I often find it nicer to just put it in a local val and “be done with it”.